T03 · Remote Payload Retrieval and Execution
Error
- Location
references/showcase-examples.md:347- Finding
Mutable Remote Installer Downloaded and Executed Directly by Bash
- Content
View full analysis
Vulnerability Details
File Location:
references/showcase-examples.md, lines 347–356
Vulnerability Type: Remote payload retrieval and execution
Risk Level: CriticalComplete Vulnerable Code Snippet:
markdown ### Option 1: Homebrew (Recommended) **Step 1: Install Homebrew** (if not already installed) ```bash /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"Step 2: Install Virtuoso
bash brew install virtuosotext ### Technical Analysis The installation example retrieves a shell script from a mutable external URL and passes its contents directly to `/bin/bash`. The `HEAD` reference is not pinned to a reviewed commit, and the command performs no checksum, signature, or content verification before execution. Although the URL points to the recognizable Homebrew GitHub repository, the effective payload can change after the Skill has been reviewed. A compromise of the upstream repository, maintainer account, distribution path, or referenced branch could therefore turn this installation instruction into arbitrary code execution. Installing an additional package manager also exceeds the minimum privileges necessary to provide Virtuoso installation assistance when Homebrew is not already installed. The installer can modify filesystem locations and shell configuration and may request administrative authorization. The document provides a separate direct installation option, so immediate execution of a remotely retrieved package-manager installer is not strictly necessary for the Skill's declared functionality. ### Attack Path 1. A user asks the Skill for Virtuoso installation instructions on macOS. 2. The Skill uses this showcase workflow and recommends Homebrew. 3. The user copies and runs the supplied command. 4. `curl` retrieves the current content referenced by `HEAD/install.sh`. 5. Bash executes that content immediately without ...[truncated 1184 chars]- Remediation
View remediation
Remediation Suggestions
- Remove the direct
curl-to-Bash command from the Skill. - If Homebrew is already installed, limit the instructions to:
bash brew install virtuoso - If Homebrew is not installed, direct the user to Homebrew's official installation documentation rather than embedding a remote execution command.
- If scripted installation must be documented:
- Pin the source to a specific reviewed commit rather than
HEAD. - Download the script to a local file without executing it.
- Verify a trusted, independently published cryptographic checksum or signature.
- Let the user inspect the downloaded script.
- Obtain explicit confirmation before execution.
- Pin the source to a specific reviewed commit rather than
- Clearly disclose expected filesystem modifications and any administrative authorization the installer may request.
- Prefer signed official Virtuoso packages or another installation path that does not require installing an additional package manager.
- Add a general policy preventing generated support responses from recommending download-and-execute pipelines such as
curl | sh,wget | bash, or command-substitution equivalents.
- Remove the direct